I'm still confused about the skill system, I don't understand the " minimum levels needed ", I just wonder if there is a way to know when the next skill level will be available? Currently I just kill things, level up and hope that the next skill level is available

I guess this was changed from the vanilla version due to level 125 and all the new runes and runewords, am I right? Hopefully the skill system could be tweaked to be less confusing for new players like me